nanog mailing list archives

Re: NTP question


From: Mel Beckman <mel () beckman org>
Date: Thu, 2 May 2019 03:30:03 +0000

Yo Gary!

Not only did I not sleep through it, I was one of the engineers who verified that every GPS clock source in a very 
large aviation support network didn’t have have this bug. 

I’m also an FAA licensed A&P mechanic, and have worked for airlines in fleet maintenance.  Air carriers have extremely 
thorough systems reviews, by law, through the Airworthiness Directive program, which started identifying 2019 GPS 
rollover vulnerabilities in ... 2009! Nobody was surprised.  If any GPS systems “went nuts”, it was through the 
incompetence and negligence of their owners.

 -mel 

On May 1, 2019, at 8:03 PM, Gary E. Miller <gem () rellim com> wrote:

Yo Mel!

On Thu, 2 May 2019 02:54:25 +0000
Mel Beckman <mel () beckman org> wrote:

Why? The GPS NTP Server is Stratum-1.  If it fails computer clocks
will freewheel for hours or days before losing significant time,
during which period you can simply order a replacement unit. If that
isn’t fast enough, buy two $300 boxes. The “consensus” issue is moot,
since a GPS server gets a consensus of clock time from the GPS
satellite constellation. 

I guess you slept through GPS Week Roll Over day last April 6th?

Some GPS went nuts, others did not.  Many 777 and 787 were grounded that
weekend for software updates to their expensive Honeywell GPS.  I'll
spare you the many more examples that hapened.

Not nice when yoar clock rolls back to 1999, or forward to 2035.

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
   gem () rellim com  Tel:+1 541 382 8588

       Veritas liberabit vos. -- Quid est veritas?
   "If you can’t measure it, you can’t improve it." - Lord Kelvin

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